Vehicles operating in an autonomous mode (e.g., driverless) can relieve occupants, especially the driver, from some driving-related responsibilities. When operating in an autonomous mode, the vehicle can navigate to various locations using onboard sensors, allowing the vehicle to travel with minimal human interaction or in some cases without any passengers.
Motion planning and control are critical operations in autonomous driving. For example, throttle, brake, and steering commands are most important commands in autonomous driving. These commands are generated and issued based on an assumption of a flat road. When a vehicle is driving a sloped road (e.g., uphill or downhill road), the same commands will typically be generated and issued, which may not be desirable.